1. Field of the Disclosure
The present disclosure relates to a method and apparatus for acquisition of a public IP (Internet Protocol) address of a mobile station in order to provide a push service, in a communication system.
2. Description of the Related Art
A push service is a service in which, when update data is generated, an application server transmits the corresponding data to a mobile station without a request of the mobile station. Through this, when new data is generated, the mobile station can receive the data.
In order that the push service is made possible, the application server must be able to first set an IP session to the mobile station. That is, if there is data to be transmitted to the mobile station, the application server must be able to first set an IP session to the mobile station and transmit the data to the mobile station.
However, a mobile network service provider cannot secure a sufficient number of public IP addresses due to several problems. Instead, the mobile network service provider installs, in a network of the mobile network service provider, a gateway that uses a NAT (Network Address Translation) technology, and allocates private IP addresses to mobile stations within the network.
The mobile station within the mobile network service provider network can set up IP sessions with mobile stations outside the mobile network service provider network, using the allocated private IP addresses, and perform communication with the mobile stations outside the mobile network service provider network.
However, due to the private IP allocation, equipment outside the mobile network service provider network cannot first set an IP session to the mobile station within the mobile network service provider network. It is because the private IP address is an effective IP address only within the mobile service provider network.
To address this problem, the application server sets up a continuous IP session with the mobile station and provides a push service through this. To maintain the continuous IP session, the mobile station transmits a keep alive message to the application server by periods. The keep alive message enables the gateway to refresh a NAT table by periods and enables the IP session to be kept being continued.
However, this generates a signaling overhead and is the cause of wireless resource waste. If an N number of mobile stations and an M number of application servers exist, an M×N number of continuous IP sessions exist between the mobile stations and the application servers, and signaling generated to maintain the continuous IP session is a big burden to the network.
Also, because even the mobile station has to transmit the keep alive message by periods so as to maintain the M×N number of continuous IP sessions, there is a problem in which wireless resource waste and power consumption are great.